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/***************************************************************************

 *   Copyright (C) 2007, 2008 by Andreas Theofilu                          *

 *   andreas@theosys.at                                                    *

 *                                                                         *

 *   This program is free software; you can redistribute it and/or modify  *

 *   it under the terms of the GNU General Public License as published by  *

 *   the Free Software Foundation version 3 of the License.                *

 *                                                                         *

 *   This program is distributed in the hope that it will be useful,       *

 *   but WITHOUT ANY WARRANTY; without even the implied warranty of        *

 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the         *

 *   GNU General Public License for more details.                          *

 *                                                                         *

 *   You should have received a copy of the GNU General Public License     *

 *   along with this program; if not, write to the                         *

 *   Free Software Foundation, Inc.,                                       *

 *   59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.             *

 ***************************************************************************/

#include <iostream>

#include "transform.h"

using std::cout;

using std::cerr;

using std::clog;

using std::endl;

transform::transform(double _llat, double _llon, double _rlat, double _rlon)

{

	llat = _llat;

	llon = _llon;

	rlat = _rlat;

	rlon = _rlon;

	MapLatCtr = (rlat - llat) / 2.0 + llat;

	MapLonCtr = (llon - rlon) / 2.0 + rlon;

	MapXCtr = MapYCtr = 0;

	xscale = yscale = 0.0;

	width = height = 0;

}

transform::~transform()

{

}

/*

 * Set the dimensions in pixels of the image and calculate the scaling.

 */

void transform::setDimensions(int _width, int _height)

{

	width = _width;

	height = _height;

	MapXCtr = width / 2;

	MapYCtr = height / 2;

	xscale = 1.0 / ((double)width - 1.0);

	yscale = -1.0 / ((double)height - 1.0);

	PixPerLatDeg = width / (llat - rlat);

	PixPerLonDeg = height / (rlon - llon);

}

/*

 * Set the scale of the image.

 * This function makes only a rudimentary check of the given values

 * and overwrites the previous values if no errors were found.

 */

void transform::setScale(double scx, double scy)

{

	if (scx <= 0.0 || scx > 1.0 || scy >= 0.0 || scy < -1.0)

	   return;

	xscale = scx;

	yscale = scy;

}

/*

 * Return the current scale of X andd Y dimensions

 */

void transform::getScale(double *scx, double *scy)

{

	*scx = xscale;

	*scy = yscale;

}

/*

 * Calculate the pixel position on a raster map out of the

 * geo coordinates given in radian.

 */

bool transform::latLonToPix(double plat, double plon, int *px, int *py)

{

int x,y;

double lat, lon, xdist, ydist, dist, az, pixdist;

	lat = plat;

	lon = plon;

	ydist = PixPerLatDeg * (lat - MapLatCtr);

	xdist = PixPerLonDeg * (lon - MapLonCtr);

	az = atan(ydist / xdist);

	if (xdist < 0.0)

	   az += M_PI;

	dist = (xdist * xdist) + (ydist * ydist);

	pixdist = sqrt(dist);

	x = (int)(MapXCtr + pixdist * cos(az));

	y = (int)(MapYCtr - pixdist * sin(az));

	*px = x;

	*py = y;

	return true;

}

/*

 * Calculate the offset inside an image. This value can be used in a

 * buffer as an index, for example.

 */

long transform::getOffset(double plat, double plon)

{

int x, y;

	latLonToPix(plat, plon, &x, &y);

	return ((long)width * (long)y + (long)x);

}